1. Field of the Invention
The present invention relates generally to deployment devices for parachutes and particularly to a device which can be used at both low and high deployment speeds.
2. Description of Related Art
Parachutes are commonly packed in a bag or sleeve which is attached to a first end of a bridle cord. A pilot chute is attached to a second end of the bridle cord. The parachute lines are stowed on or in this bag or sleeve in such a way that the lines must be fully extended before the parachute may come out of the bag. The entire system just described is then packed into its container. The pilot chute is deployed manually or by the action of a spring built into the pilot chute itself, with the container being opened in the process. The pilot chute creates drag from the airflow, which in turn lifts the bag or sleeve out of the container, extending the lines in the process. Once the lines are extended, the bag or sleeve is opened and the parachute is released into the airflow and inflates.
If a parachute is designed to deploy quickly at low airspeeds, the pilot chute must be of a high-drag variety, in order to develop enough force to extract the bag from the container quickly, extend the parachute lines, and release the canopy so that it can then inflate. If the pilot chute does not create enough drag at low speeds, then the parachute may not deploy. If this low speed parachute system is then deployed at higher speeds, the high drag pilot chute will develop too much force, which may cause deployment system damage, canopy damage, or a malfunction of the parachute due to an out-of-sequence deployment.
If a parachute is designed to deploy at high speeds, a smaller, low-drag pilot chute is used to keep the drag down to an appropriate level and maintain order in the deployment sequence. However, the small, low-drag pilot chute of this high-speed system will not have enough drag to reliably deploy the parachute at low speeds.
Therefore, deployment systems are usually a compromise between having enough drag at low speeds to deploy the parachute, but not so much drag at high speeds that it creates the problems described above. This compromise limits the speed range of the typical parachute system. It is therefore to these shortcomings to which the present invention is directed.